Batteries: What’s here versus what we need

Solving two battery challenges—one for the electric grid, one for cars.

We mostly think of batteries in terms of gadgets like phones and laptops. Although we'd all love lighter weight, higher capacity, and faster charging for our gadgets, progress for this type of battery has for the most part already made huge strides. The modern battery is largely keeping pace with our needs.

But two other big potential users of batteries—the electric grid and automobiles—haven't really found the better technology they need. Based on a panel discussion at this year's meeting of the American Association for the Advancement of Science, that's more of a challenge than it sounds, since the two battery uses need very different things.

What the grid needs

The grid perspective was handled by Haresh Kamath of the Electric Power Research Institute. He began his talk by noting that the whole purpose of the grid is to let you disconnect the generation of power from its use in space, letting people take advantage of efficiencies of scale and location. Energy storage does the same thing but across time, allowing power to be generated when it's cheapest and then used as needed.

So far, however, storage has meant pumped hydropower or compressed air, both of which require specific geologies to make sense. On the other hand, batteries can go pretty much anywhere and perform a variety of functions beyond simply holding onto electricity for future use. They can help regulate the grid's frequency, and their distributed nature can help with stability in cases of equipment failure. But since the grid hasn't historically had much storage, these factors are treated as intangibles and priced accordingly.

That situation is starting to change as a regulatory structure is put in place and states begin to consider mandating a certain level of utility-grade storage. Notably, California now has a mandate for 1.3GW·h of storage.

The challenge will be that very few of the battery technologies available in mass quantities offer what the utilities need: "Utilities want 15-20 year life spans and minimal maintenance," Kamath said. And they have to deliver that at a price of about $500 per kilowatt-hour (kW·h) to make economic sense. This only works if the intangibles Kamath mentioned are actually given a price. Lithium batteries are only getting close to being there price wise, but they don't offer the durability the utilities need.

What the automakers need

What lithium batteries do have is a relatively low weight for the energy they store, which fits the needs of a different market—cars. GM's director of fuel cell research, Mark Mathias, was in attendance to speak for the automakers. His field might seem like an odd match for batteries, but it's more relevant than you might think. "In our mind, fuel cell vehicles are electric vehicles," Matthias said. "In this case, you're just making the electricity on the vehicle." And if you're making an electric vehicle, you have to decide when it makes sense to generate that electricity, or when it's better to store it.

In some ways, Mathias suggested, current lithium batteries are doing pretty well. He noted that plug-in hybrids are already ahead of where the Prius was at this point in its history, and he referred to the "surprise" of what Tesla could accomplish at the high end.

But there are limits that hit hard. One is weight. For a midsized vehicle to cover a range similar to existing vehicles (about 300 miles), you need about 100kW·h of battery. That's possible with lithium, Mathias said, but it adds a lot of weight to the car. Then there's refueling. Gas can be put back into a car at a rate of about 150 miles of travel per minute; the equivalent value for hydrogen is 100 miles per minute. Even with a supercharger, the figure for batteries is about six.

Of course, grid-based electricity crushes both gasoline and hydrogen on a key item: price. Thus, GM continues to evaluate developing technologies. So far, Matthias isn't optimistic. He noted that lithium-sulfur batteries have a very low cost, but performance degrades too fast for the car's lifetime. Lithium air currently requires partly purified oxygen, and the chemistry is not as reversible as it needs to be. Other metal-air batteries pose similar problems.

In Matthias' view, we need a battery revolution before fuel cells would stop making sense.

You say you want a revolution?

Jeff Chamberlain of Argonne National Lab would be happy to oblige. He's part of a project called 5X, the goal of which is to get storage down to $100 per kW·h (it's currently at $500) at five times the energy density, all within five years. That sounds insanely ambitious, but he said that theoretical calculations suggest that a 10x improvement should be possible, and achieving half the theoretical maximum was typical of mature tech. But he also suggested that looking past the current battery development process is probably necessary.

Typically, people have just looked carefully at the periodic table and chosen their materials accordingly. Chamberlain said that the people at Argonne were working to understand what happens at the atomic level during energy storage. And they were thinking about very different materials and structures. Instead of lithium, they were considering anodes made of metals that can give up two or more electrons. For the cathodes, they pondered a flow material that can intercalate ions while continuing to bring fresh material to the cathode. In between, the answer might be a non-aqueous electrolyte.

Right now, the researchers are still mostly in the simulation phase. But if they succeed and the resulting batteries have the sort of life span that utilities need, then it may be possible to create one battery that satisfies the needs of two very different markets.

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Also, I'm curious why the article doesn't mention several of the other exciting lines of research.

For grid scale storage, there's http://www.lightsail.com/ which uses water injection to substantially improve loss efficiencies of compressed air storage. Compressed air, like pumped hydro, has advantages for grid storage because the storage capacity can be scaled independently of the power capacity (bigger storage tanks vs more compressors).

Talking about grids, why they don't transform energy surplus in tanks of H2 and O2 and back in H2O when in need?

A little thing called the Second Law of Thermodynamics.

"Lisa, in this house, we obey the laws of thermodynamics!"

That being said, there are going to be losses no matter how things are stored. At least H2 and O2 would provide a way of storing energy right now, with our current level of technology rather than waiting for something better to come along.

Talking about grids, why they don't transform energy surplus in tanks of H2 and O2 and back in H2O when in need?

A little thing called the Second Law of Thermodynamics.

"Lisa, in this house, we obey the laws of thermodynamics!"

That being said, there are going to be losses no matter how things are stored. At least H2 and O2 would provide a way of storing energy right now, with our current level of technology rather than waiting for something better to come along.

The problem is that while there are solution today that can work, in many cases they are not cost effective to use. Getting H^2 and O would require water (something states have an issue with) and power or materials for splitting water apart. The problem is, last I checked, breaking down water was very power hungry and has a rather low efficiency. So it would not serve as an efficient way to store excess power generation.

The next problem is the efficiency of fuel-cells to convert that power back into electricity. There is another loss that would hamper the process. There is also scaling issues. It is not an easy issue to solve...after all, if it was easy...why hasn't someone solved it by now.

The development of improved battery technologies is a very interesting area that could potentially have a huge impact over a wide range of applications. I'm looking forward to seeing how some of these ideas pan out.

What ever happened to Graphene Gel super-batteries? Charge in 6 seconds, have far more energy density, supposed to be cheap (just a few minor issues of mass production to work out, I'm sure ;-) ).

Back about a year ago, there were articles coming out every 2 weeks about some new discovery related to Graphene. I definitely remember seeing articles about Graphene Gel to create superbatteries. Is this happening, or not? Why no discussion here?

Also, I'm curious why the article doesn't mention several of the other exciting lines of research.

For grid scale storage, there's http://www.lightsail.com/ which uses water injection to substantially improve loss efficiencies of compressed air storage. Compressed air, like pumped hydro, has advantages for grid storage because the storage capacity can be scaled independently of the power capacity (bigger storage tanks vs more compressors).

Both of which seem more promising for grid storage than yet another battery chemistry.

Actually, batteries can also be scaled somewhat separately in terms of power and energy, asfaik its a reaction area to volume thing. Flow batteries (check out NGK NAS) definitively scale P&E independently.

The Lightsail has a nice homepage but I could not find any real refs to their performance and progress..

Typical CAES plants (the only two that exists, and have for 20y+) are connected to coal plants in order to exchange heat for compression/decompression stages. I wonder - how does Lightsail store the heat needed to keep efficiency up, especially in the smaller (which usually equals less efficient) units they propose?

Durability wouldn't necessarily be such a big issue if you could get the price down enough. Utilities care about amortized cost, so a super-cheap battery that lasted 5 years would be just as good as a mid-cheap one that lasted 20. (sure, they'd like the longer life because then you don't spend on the replacing job, but the power indsutry is perfectly used to longterm consumables.)

For power grid storage, why not consider supercapacitors? Very high cycle life and current density. Not very good energy density but that would be fine for large installations where there's room for a large footprint. Only drawback is self discharge rate when compared to a battery, but still you're talking days worth of charge storage which seems like enough for momentary demand spikes and short term power generation loss.

I could stand to lose about five pounds, haven't run in a while and need to start back.

I'm sort of a new urbanist, so it's not hate. It's certainly technically possible for us to deal with a number of our transport issues by applying early 20th century technology: Dense development and mass transit.

There was an Ars article not long back about a huge improvement to Lithium-air. Since it's not commercially implemented, it might not be considered when giving a panel, but I think it - like many advances - will be what incrementally bring us to the next step. Lithium-air all by itself would be a gigantic advance, and I can't help think perhaps Tesla knows it with their new factory.